Methylcyclopentene production



Oct. 25, 1949. G. M. GOOD ETAL METHYLCYCLOPENTENE PRODUCTION Filed sept. 29, 1947 IXInUQ Gea/ge M 6'000 /fefve /nvenfarw Patented Oct. 25, 1949 UNITED sTATEs PATENT OFFICE' METHYLCYCLOPENTENE PRODUCTION y George M. Good, Albany, and Hervey H. Voge, Berkeley, Calif., assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application September 29, 1947, Serial No. 776,7.65

Claims. l

This invention relates to the Aproduction of y cyclic oleilns consisting essentially of methylcyclopentenes in a state of high purity. More particularly the invention relates to the production of cyclic olens consisting essentially of methylcy- 5 clopentenes of high purity from complex hydrocarbon mixtures comprising methylcyclopentenes vin admixture with close boiling hydrocarbons.

A particular aspect of the invention relates to the production of cyclic tertiary oleiins consistl0 ing essentially of l-methylcyclopentene from hydrocarbon mixtures comprising l-methylcyclopentene and 4-methylcyc1opentene in admix-y ture with close boiling hydrocarbons.

yThe methylcyclopentenes are valuable as interl mediate and starting materials in the production of many valuable chemical derivatives. The need Y for these unsaturated cyclic compounds, in a state of relatively high purity, has rendered highly desirable suitable means enabling their more ecient production from readily available sources. Sources of the methylcyclopentenes comprise the oleiinic hydrocarbon mixtures resulting from the thermal or catalytic treatment of naturally occurring or synthetically produced hydrocarbons or carbonaceous materials. The olenic hydrocarbon inixtures boiling in the motor fuel boiling range obtained, for example, by the catalytic cracking of hydrocarbons, generally contain a substantial amount of methylcyclopentenes. The

complexity of these hydrocarbon mixtures and. the presence therein of a multiplicity of hydrocarbons boiling at temperatures in close proximity to the boiling temperatures of the methylcyclopentenes renders extremely dimcult and ol'ten impossible the separation therefrom of these unsaturated cyclic hydrocarbons in a relatively high state of purity by methods available heretofore. The complexity of operative steps required,

and in some cases the need for the use of catalysts 40 or reagents of relatively high cost, to product methylcyclopentenes of a sufficient degree of purity by methods available heretofore, often render these processes highly impractical as a source of the desired unsaturated cyclic compounds. The diilculty of separating even a single one of the methylcyclopentene isomers from such hydrocarbon mixtures by methods available heretofore is rendered apparent by a realization of the multiplicity of hydrocarbons having approximating boiling temperatures generally present therein. Thus a hydrocarbon fraction consisting essentially of hydrocarbons having six carbon atoms to the molecule and having a boiling range of to 69 C., separated from an olenic 55 cracked gasoline by fractionation will generally contain 3-methylcyclopentene in adm ixture with the closely boiling hydrocarbons indicated in the following table:

Table A I 0. 2-ethy1butene-1 65 3,-methy1cyclopentene 67 2-methylpentene-2 67 3-methylpentene-2 (trans) 68 Hexene-3 (cis)- 68 Hexene-3 (trans) 68 Hexene-2 (cis and trans) 68 n-Hexane 69 A fraction of such unsaturated cracked hydrocarbons boiling in the range of from '70 to 83 C. will generally contain 4-methylcyclopentene, 1- methylcyclopentene and methylenecyclopentane in admixture with the close boiling six carbon atlon hydrocarbons indicated in the following Table B C. 3-methylpentene-2 (cis) 71 Methylcyclopentane 72. 2,3-dimethylbutene-2 73 4-methylcyclopentene 75 l-methylcyclopentene 76 Methylenecyclopentane 76 Benzene 80 Cyclohexane 81 Cyclohexene 83 Close boiling hydrocarbons other than the xsix carbon atom hydrocarbons are generally encountered which further 'complicates the problem of separation as evidenced from the following table of seven carbon atom aliphatic hydrocarbons Iboiling in the ran-ge of from 72 to 85 C. encountered in olenic cracked gasolines.

The relatively wide spread in boiling range of the three methylcyclopentene isomers and the fact that the practicality of a process for the production of relatively pure methylcyclopentenes is often dependent upon a recovery of `at least the greater part of all three, renders the use of processes involving such steps as fractionation and olefin extraction, as utilized heretofore, highly unsatisfactory.

It is an object of the present invention to provide an improved process for the more efficient production of cyclic oleflns consisting essentially of methylcyclopentenes in a, relatively high state ot purity from oleflnic hydrocarbon mixtures comprising methylcyclopentene in admixture with close boiling hydrocarbons inseparable therefrom on a practical scale by methods available heretofore.

Another object of the invention is the provision of an improved process for the more emcient production of cyclic olens consisting essentially mixture with close boiling hydrocarbons inseparable therefrom o'n Aa practical scale by methods available heretofore.

A more particular object of the invention is the provision of an improved process for the more eflicient production of 1methylcyclopentene of high purity from hydrocarbon fractions comprising l-methylcyclopentene and 4-methylcyclopentene in admixture with close boiling open chain hydrocarbons. Other objects and advantages of the invention will become apparent from the following detailed description thereof.

In co-pending application Serial No. 776,763 iiled September 29, 1947, of which the present application is a continuation-impart, there is disclosed and claimed a method for the production of methylcyclopentenes of high purity from hydrocarbon mixtures comprising methylcyclopentenes in admixture with close boiling open chain aliphatic hydrocarbons. In the method of the patent application the l-methylcyclopentene is obtained, however, in admixture with substantial amounts of l-methylcyclopentene, and the process does not lend itself to the eiiicient recovery of the methylcyclopentene content of the complex hydrocarbon charge in the form of only the l-methylcyclopentene. Of the methylcyclopentene isomers, the l-methylcyclopentene is of particular value because of the presence of atertiary olefinic bond. Methylenecyclopentane, which at times may be present in smaller amounts, and which will be separated with the 1-methy1cyclopentene according to the method of 'the present invention, is also a tertiary olen and willgenerally give rise to chemical derivatives similar to oridentical with those obtained from l-methylcyclopentene in chemical processing.

In accordance with the process of the invention,

.methylcyclope'ntenes are produced from complex olenic hydrocarbon mixtures comprising methylcyclopentenes in admixture with close boiling aliphatic hydrocarbons, with recovery of at least the greater part of said methylcyclopentenes in a high state of purity, by separating from said hydrocarbon mixture a hydrocarbon fraction comprising B-methyIcycIopentene and a hydrocarbon fraction comprising l-methylcyclopentene and 4-methylcyclopentene and separately treating said fractions under the conditions defined fully herein to recover at least a substantial part of the methylcyclopentene content therefrom. In a preferred method of carrying out the process of the invention at least a substantial part of the methylcyclopentene content oi the complex hydrocarbon charge is recovered as 1-methylcyclopentene of high purity.

The objects and advantages of the invention are.

obtained by f ractionating a complex olei'lnic hydrocarbon mixture comprising methylcyclopentenestion is subjected to olefin isomerizing conditions in a rst isomerizing zone eiicting the conversion of S-methylcyclopentene to cyclic oleiins comprising I-methylcyclopentene and 4-methylcyclopentene. The higher boiling fraction is subjected to tertiary olefin separating conditions, such as, for example, contact with an agent selectively combining with, or absorbing, the l-methylcyclopentena in a tertiary olefin separating zone. Hydrocarbons comprising A4-methylcyclopentene in admixture with close boiling open chain hydrocarbons are separated from the eliluence of the tertiary olefin separating zone and separately subjected to olefin isomerizing conditions in a second olefin isomerizing zone effecting the conversion of 4-methylcyclopentene to cyclic olens comprising 1methylcyclopentene- Eiiiuence from the 'second isomerizing zone is returned to the tertiary olen removing zone to eiect .the removal of l-methylcyclopentene therefrom. l-methylcyclopentene in a high state of purity is separated from the eiiiuence of the tertiary olefin separating zone.

Optionally S-methylcyclopentene in a high state of purity may be fractionated from the efliuence of the second isomerizing zone and eliminated from the system as a final product. The process of the invention thus provides a highly flexible and efficient method for not only converting substantially the entire methylcyclopentene content of the complex hydrocarbon charge to methylcyclopentenes in a high state of purity but for the conversion of a substantial part of the methylcyclopentene content of the charge to l-methylcyclopentene of high purity.

In a preferred modification of the invention substantially all of the methylcyclopentene content of the complex hydrocarbon charge is converted to essentially only l-methylcyclopentene of high purity. In such preferred modification of the invention the 3-methylcyclopentene separated from the eiuence of the second olefin isomerizing zone is recycled to the second olen isomerizing zone to be converted to methylcyclopentenes comprising 1-me'thylcyclopentene catalytic treatment of hydrocarbons, .such as, for

example, the methylcyclopentene-containing hydrocarbon mixtures obtained in the thermal and catalytic cracking, dehydrogenation, destructive dehydrogenation, reforming, and the like, of hydrocarbons.

In order to set forth more fully the nature of the invention, it will be described herein with reference to the attached drawing wherein the single figure represents a more or less diagrammatical elevational view of one form of apparatus suitable for executing the process of the invention.

Referring to the drawing, a complex olelnic hydrocarbon mixture comprising methylcyclopentenes in admixture with close boiling aliphatic hydrocarbons, such as, for example, a catalytically cracked gasoline, taken from an outside source is forced through valved line I0 into a feed fractionating zone. In the feed fractionating zone, the hydrocarbon charge is fractionated to separate therefrom a lower boiling fraction comprising 3-methylcyclopentene in admixture with close boiling aliphatic hydrocarbons and a higher boiling fraction comprising 1- methylcyclopentene and .4-methylcyclopentene in admixture with close boiling aliphatic hydrocarbons. The feed fractionating zone is indicated in the drawing by fractionators II, I2, I3 and I4. Within fractionator I I a vapor fraction comprising hydrocarbons boiling below about 66 C. is separated as a vapor fraction from a liquid fraction comprising hydrocarbons boiling above about 66 C. The liquid fraction is passed from fractionator II through line I6 into fractionator I2. Within fractionator I2 a fraction comprising substantially all of the methylcyclopentene content of the charge, such as, for example, a fraction having a boiling range of from about 66 C to about 77 C., is separated as a vapor fraction from a liquidfraction comprising hydrocarbons higher boiling than about 77 C. The vapor fraction comprising isomeric methylcyclopentenes in admixture with close boiling aliphatic hydrocarbons is passed from fractionator I2 by means of line I'I into fractionator I3. Within fractionator I3 a vapor fraction comprising 3- methylcyclopentene in admixture with close boiling hydrocarbons, such as, for example, a fraction boiling in the range of from about 66 C. to about 68 C. is separated as a vapor fraction from a. liquid fraction comprising hydrocarbons boiling in the range of about 68 C. to about 77 C. The vapor fraction comprising 3-methylcyclopentene is taken overhead from fractionator I3 through line I8 and forms the charge to a first reaction zone.

The liquid fraction is passed from fractionator I3 through line I9 into fractionator I4. Within fractionator i4 a vapor fraction comprising methylcyclopentane, such as, for example, a fraction boiling in the range oi.' from about 68 C1074? C.,.is separated from a liquid reaction comprising substantially all of the l-methylcyclopentene and 4-methylcyclopentene originally present in 'the charge in admixture with close boiling aliphatic hydrocarbons, such as, for example, a fraction boilingin the range of from about 74 C. to about 77 C. The liquid fraction comprising l-methylcyclopentene and 4-methylcyclopentene is taken from fractionator I4' by means of line 2liv and forms the charge to a separate reaction zone of the process. Y

The 3-methylcyclopentene-containing fraction ilowlng through line I8 will comprise a plurality -of open chain olenic hydrocarbons having six carbon atoms to the molecule boiling at, or close to, the boiling temperature of` 3-methylcyclopentene and therefor inseparable therefrom on a practical scale by such cxpedients as fractionation.

The methylcyclopentene-containing fraction is passed from line I8 into a heating zone, such as, for example, an externally heated coil 2| positioned ina furnace structure 22. From heating coil 2|, the heated S-rnethylcyclopentene fraction is passed through line23 into a suitable first reaction zone. The lrst reaction zone may comprise a reaction chamber 24.

A hydrocarbon fraction consisting essentially of S-methylcyclopentene in admixture with closeboiling aliphatic hydrocarbons may be introduced into line I8 from an outsidesource by means of valved line 21. Such hydrocarbon fraction introduced into the system by means of line 21 may comprise a part or all of the S-methylcyclopentene fraction introduced into the first reaction zone.

' Within reaction chamber 24, the 3-methylcyclopentene fraction is contacted with an olen isornerization catalyst at olen isomerizing conditions set forth fully below, eiecting the conversion of 3-rnethylcyclopentene to unsaturated cyclic olei'ins consisting essentially of lmethylcyclopentene, 4methylcyclopentene and a minor amount of cyclohexene. Under the isomerizing conditions maintained in reactor 24 at least a substantial part of the six carbon atom open chain oleiins are simultaneously converted 50,/ to isomeric open chain olens boiling below 66 C. Isomerization of the B-methylcyclopentene fraction under these conditions is illustrated by -the following example:

Example I An oletinic hydrocarbon fraction having a boiling range of from about 66 C. to about 68 C., separated from a catalytically cracked gasoline by fractionation, and having a B-methylcyclopentene content of 40% and an open chain Cs oleiin content of 55% is contacted with a bauxite catalyst at a temperature of 275'C. and atmospheric pressure. A conversion of S-methylcyclopentene to 1 methvlcyclopentene and 45- methylcyclopentene of '70%. and of open chain olefins to olens boiling below 66 C. of 30% is obtained. Only about 1.42% of the B-methylcyclopentene is converted to cyclohexene.

Eiiiuence from reactor 24 comprising l-methylcyclopentene, 4-methy1cyclopentene, unconverted -r'nethylcyclopentene, traces of cyclohexene, and the open chain isomerizedand unisomerized six carbon atom olens is passed through line 29, provided with suitable cooling means, such as, for example, a heat exchanger 30, into a. product separating zone. Since the highest boiling noncyclic Cn olefin boils at 73 C., and l-methylcyclopentene, 4methylcyclopentene', and cyclohexene boil at 75, 76, and 83 C., respectively, the 1- and iL-methylcyclopentenes along with the cyclohexene are readily separated from the reactor efuence by fractionation.

The product separating zone receiving reaction products from line 29 is depicted in' the drawing by fractionators 3l and 32. Within fractionator 3| a vapor fraction comprising isomerized open chain olefins boiling below 66 C. is separated from a liquid fraction comprising hydrocarbons boiling above 66 C. The liquid fraction is passed from fractionator 3-l through line 34 into a fractionator 32. Within fractionator 32 hydrocarbons comprising 1-methylcyclopentene, 4-methylcyclopentene as well as traces of cyclohexene are separated as a liquid fraction from a vapor fraction having a boiling range of about 66 to about 74 C. comprising unconverted S-methylcyclopentene in'admixture with close boiling aliphatic olefins. At` least a part of the vapor fraction is recycled from fractionator 32, through line 35, into line I8. Valved line 36 is provided to enable the bleeding of a portion of the recycle stream from the system to avoid the accumulation of saturated hydrocarbons boiling in the boiling range of the recycled stream. Although such bleeding will generally sufIice, a portion or all of the recycle stream may be byl fin liberating chamber are represented rby champassed from line through suitable saturated hydrocarbon removing means such as, for example, an\ extraction zone, not shown in the drawing. l

The liquid -fraction comprising land 4- methylcyclopentenes, now free of any substantial amount of open chain hydrocarbons, is taken from fractionator 32 through valved line 39 and eliminated from the system as la final product. Any cyclohexene mixed with the methylcyclopentenes taken from valved line 33 is readily separable therefrom by fractionation.

The hydrocarbon fraction passing through line 20,' comprising 1-methylcyclopentene and 4- methylcyclopentene separated from the charge will comprise open chain heptenes having boiling temperatures closely approximating those of the methylcyclopentenes contained in the stream. These methylcyclopentene isomers are therefore inseparable from the open chain hydrocarbons .admixed therewith, or from each other, by ordinary fractionating means. In accordance with the process of the invention the hydrocarbon stream flowing through line 20 is passed into a tertiary olen separating zone.

Within the tertiary olefin separating zone the hydrocarbon stream is contacted with a treating agent such as a selectively reacting chemical agent'capable of selectively reacting or combin-` ing with, or selectively absorbing, the cyclic tertiary olefln 1-methylcyclopentene- The tertiary olefin separating zone will generally comprise an olefin removing chamber wherein the tertiary cyclic olefin selectively reacts or combines with, or is selectively absorbed by, the tertiary olefin separating agent employed, and a tertiary olefin liberating chamber wherein the tertiary cyclic olen (l-methylcyclopentene) is liberated from the reaction product, or rich absorbing medium, comprising it formed in the tertiary oleiin re` moving zone. The tertiary olen removing and liberating chambers may consist of separate sec- 1 tions comprised in a single vessel or may consist of'separate vessels. In the drawing the tertiary bers 42 and 43, respectively.

' Additional hydrocarbons from an outside source consisting essentially of 1- and li-methylcyclopentenes in A'admixture withy close boiling open chain hydrocarbons having seven carbon atoms to the molecule may be introduced into the system by means of valved line 45. Such hydrocarbons introduced into the system through valved line 45 may constitute a part or all of the hydrocarbons comprising ,1- and 4-methyl-v cyclpentenes in admixture withl close boiling open chain hydrocarbons introduced into tb^ system.

Within chamber 42 the hydrocarbon stream 1- and 4-methylcyclopentenes is contacted with a suitable treating or selectively reacting tertiary olefin separating agent, such as a chemical agent capable of entering into selective compound formation with the tertiary cyclic olefin, 1-methylcyclopentene, under compound-formingl conditions. Thus the hydrocarbon stream may be contacted with a suitable alkylatable material under alkylating conditions within chamber 42. Suitable alkylatable materials comprise, for example, the phenols such as the hydroxy aromatic compounds exemplified by phenol, cresol, resorcinol, hydroquinone, pyrogallol, naphthol, and the like. The alkylatable material, such as, for example, phenol, is introduced into chamber 42 from an outside source by means of valved line 46 provided -with suitable heating means, such as, for example,

a heat exchanger 41. Within chamber 42 the phenol is intimately contacted with the hydrocarbons comprising 1- and 4methylcyclopentenes in the presence of a suitable alkylating catalyst, such as, for example, sulfuric acid,'phosphoric acid, aluminum chloride, stannic chloride, alkyl esters of sulfuric acid, and the like.

Conventional alkylating conditions effecting the selective alkylation of the phenol with the tertiary olefin, l-methylcyclopentene, are maintained in chamber 42. Temperatures ranging for example from about 0 C. to about 150 C. are maintained within chamber 42. The specific temperature employed will, of course, vary in accordance with the particular catalyst employed. 'I'hus temperatures in the range of, for example, from about 50 to 100 C. are suitable when employing a sulfuric acid catalyst. Temperatures in the range of, for example, from about 20 to about C. are preferred when employing catalysts such as stannic chloride. `With aluminum chloridev catalysts lower temperatures, for example, from about 0 to about 50 C. are employed. Temperature conditions are maintained within chamber 42 by control of heat input into, or heat withdrawal from, the phenol stream by means of heat exchanger 41, and the hydrocarbon stream by means of suitable heating means, such as an exchanger 49, and optionally by additional temperature controlling means not 'shown in the drawing. I

It is to be stressed that the process of the invention is in no wise limited to the use of any specific alkylating conditions within chamber 42 and conventional alkylating conditions enabling the alkylation of the alkylatable material with the l-methylcyclopentene are maintained therein. Though phenols have been indicated as the preferred alkylatable material other alkylatable materials and corresponding alkylating conditions may be employed. Other suitable alkylatable materials comprise the hydroxy aromatic compounds having at least one replaceable nuclear hydrogen in the ortho or para position, such as chloro pheno1, phenol suliides, alkylphenolthioethers, etc.

catalyst employed, will entail any substantial amount of isomerization of the liberated lmeth ylcyclopentene are, however, preferably avoided.

nuclear carbon atom, will react with the phenol underv the alkylating conditions maintained within Example II A A hydrocarbon fraction separated by fractionation from a catalytically cracked gasoline, boiling in the range of '14 to 77 C., having a 1- and 4methylcyclopentene content of 70% is admixed with phenol and subjected to alkylating conditions at 85 C. in the presence of sulfuric acid. Alkylate is separated by fractionation and dealkylated by heating to 200 C. in the presence of concentrated sulfuric acid. Fractionation of the products of dealkylation results in the obtaining of l-methylcyclopentene in an amount equal to about 90% of the 1-methylcyclopentene content of the gasoline fraction subjected to alkylation.

Eiliuence from chamber 42 comprising alkylated phenol, l-methylcyclopentene, and open chain hydrocarbons is passed through line 5l provided with heat exchanger 52 into a separating chamber 53. Within separating chamber 53 a hydrocarbon layer comprising alkylated phenol and 4-methylcyclopentene is separated from a catalyst layer. The catalyst is returned to chamber 42 by means of line 55 and the hydrocarbon layer is passed through line 51 into a fractionator 59. Within fractionator 59 a vapor fraction comprising 4- methylcyclopentene and close boiling open chain hydrocarbons is separated from a liquid fraction comprising alkylated phenol.

The liquid fraction is passed from fractionator 59 through line 60 provided with suitable heating means, such as a heat exchanger 6l, into a chamber 43. Optionally, the liquid fraction may be subjected to additional separating steps to effect the removal of at least a part of any reaction products other than the alkylated phenol therefrom prior to introduction into chamber 43. Within chamber 43 the alkylated phenol is subjected to conditions effecting the liberation of the 1-methylcyclopentene from thev 1.methylcyclo pentene-phenol adduct formed in chamber 42. Conditions employed to effect the liberation of the 1methylcyclopentene may vary widely within the scope lof the invention. Thus suitable dealkylating conditions to be maintained within chamber 43 comprise a temperature at least equal to' the decomposition temperature of the alkylate assuring the splitting olf of 1-methylcyclopentene from the phenol. 'I'hus the temperature within chamber 43 may range from, for example, about 100 C. to about 450 C. The dealkylation may be .effected in the presence of a suitable dealkylation catalyst, for example, a mineral acid, such as, phosphoric acid; acid treated clay, such as an acid treated silica-alumina; bauxite; zinc chloride; zinc chloride in combination with alumina; boric acid in combination with adsorptive alumina; etc. The specific temperature employed will vary in accordance with the specific type of a catalyst employed. The use of temperatures which, in the presence of the specific dealkylation v moved therefrom through line 10.

Suitable dealkylating conditions comprise the use of sulfuric acid in the temperature range of, for example, from about C. to about 200 C.

Effluence from chamber 43 comprising l-methylcyclopentene and phenol is passed through valved line 63 into a fractionator 64. When employing a fluid dealkylating catalyst the eiiiuence from chamber 43 is passed through suitable catalyst removing means not shown in the drawing prior to passage into fractionator 64. WithinA fractionator 64 a vapor fraction comprising 1- methylcyclopentene is separated from a' liquid fraction comprising phenol. At least a part of the liquid fraction isy passed through line 65 into line 46 leading into chamber 42. A valved line 66 is provided for the elimination of a part of the recycled phenol from the system, or for its passage through suitable purifying means to avoid accumulation of any undesirable reaction products therein.

The vapor fraction consisting essentially of 1- methylcyclopentene of high purity is passed overhead from fractionator 64 through valved line 61 as a final product. K

The vapor fraction comprising l-methylcyclopentene in admixture with close boiling open chain hydrocarbons separated in fractionator 59, is re A valved line 1I is provided for the bleeding of a. part of the stream from the system. Hydrocarbons thus removed from the system through valved line 1I may be subjected to conditions effecting the removal of parafins or aromatics therefrom by means not shown in the drawing and reintroduced into line 10.

The 4-methylcyclopentene-containing hydrocarbon stream flowing through line 10 is passed into a heating zone, such as, for example, an ex ternally heated coil 15, positioned in a furnace structure 16. From coil 15 the heated hydrocaru bon stream is passed through line 11 to a second olefin isomerizing Zone of the process, such as, for example, a reaction chamber 18.

Within reactor 18 the hydrocarbon stream is contacted with an olefin isomerizing catalyst at olefin isomerizing conditions effecting the conversion of 4-methylcyclopentene to cyclic clens consisting essentially of l-methylcyclopentene and some 3-methylcyclopentene.

Isomerization of the 4-methylcyclopentene to products comprising l-methylcyclopentene in accordance with the invention is illustrated by the following example:

Example III A hydrocarbon mixture consisting essentially of fi-methylcyclopentene in admixture lwith open chain hydrocarbons of closely approximating boiling temperatures is isomerizedy by contact with a bauxitev catalyst at 275 C., `atmospheric pressure, and a liquid hourly space velocity of '7.

jA conversion of 4-methylcyclopentene to 1- and 3methylcyclopentenes of about 80% is obtained. The yield of 1-methylcyclopentene'is about 60%. Eflluence from reactor 18 is passed through line 80, provided with suitable cooling means, such as, for example, a heat exchanger 8|, into a product separating Zone. The product separatingy zone receiving eifluence from reactor 18 is depicted in the drawing by fractionators 82 and 83.

Since the boiling temperature of 3-,methylcyclopentene is 67 C. and that of the lowest boiling heptene is '72 C., separation of any Ii-methyl-l line 85 into line 10 leading into coil 15 to .effectits conversion to 1methylcyclopentene.

The liquid fraction is passed from fractionator 82 through line 89 into fractionator 83. Within fractionator 8,3 a vapor fraction comprising lmethylcyclopentene and unconverted -i-methylcyclopentenes in admixture with close boiling heptenes is separated as a vapor fraction from a liquid fraction boiling above about 84 C. comprising higher boiling materials including isomeric open chain C'z oleiins formed within the system. The liquid fraction is taken from fractionator 83 through valved line 81 and eliminated from the system. The vapor fraction comprising 1- and ll-methylcyclopentenes is recycled from fractionator 83 by means of line 90 into line 20.

Catalysts employed in reactors 24 and 18 comprise any olefin isomerization catalyst of the solid type. Suitable solid olefin isomerization catalysts comprise, for example, the naturally occurring or synthetically prepared solid adsorptive aluminous materials, such as: the aluminum oxides, activated alumina. bauxite, silica-alumina, etc. These catalytic materials may be subjected to a pretreatment before use. Such pretreatments comprise, for example. subjection to elevated temperatures, optionally in the presence of gaseous materials such as hydrogen, nitrogen, steam, gases comprising them, or the catalysts may be contacted with an inorganic mineral acid such as hydrochloric acid, sulfuric acid, carbamic acid, hydrouoric acid, boric acid, etc. A particularly preferred type of catalyst comprises adsorptive aluminous materials containing substantial amounts of .gamma alumina which has been pretreated with an acidic material. Although adsorptive materials are preferred as catalysts for the isomerization of the methylcyclopentenes, the invention is not .necessarily limited thereto and other catalysts capable of activating the oleiin isomerization reaction may be employed. Such catalysts comprise for example, catalysts of the type of naturally occurring siliceous materials such as clays, bentonites, or the like, alumina-silica compounds or mixtures thereof; zeolites; oxides of Be, Si, Tl, Th, V, Zr, Mn; etc. Other suitable catalysts are those comprising phosphoric acid and silica, as well as any acid of low volatility preferably on a solid oxide support material. Of the isomerization catalysts, those consisting essentially of alumina are somewhat preferred.

Temperatures within reactors 24 and 18 are maintained in the ran'ge of from about 150 C. to about 650 C., and preferably from about 200 C. to about 350 C. Temperature conditions in reactors 24 and 18 are 'controlled by the heat input into the hydrocarbon streams fiowing through externally heated coils 2| and 15, respectively. The isomerization reactions are preferably executed in the vapor phase. Atmospheric, or superatmospheric pressures may be maintained Within reactors 24 and 18. Pressures close to atmospheric have been found satisfactory. Throughput rates in terms of a liquid hourly space velocity of, for example, from about 0.5 to about 25 are employed.

Under/the above-defined conditions 3-methylcyclopentene is converted to cyclic oleins consisting predominantly of 1- and 4-methylcyclopentenes in reactor` 24; and 3- and 4-methylcyclopentene are converted to cyclic olens consisting essentially of 1-methylcyclopentene in reactor 18. Formation of undesirable by-products due to side reactions such as hydrocarbon degradation and polymerization yare readily mainf tained at a minimum.

In a preferred modification of the invention the land ir-methylcyclopentenes emanating from reactor 24 are passed from line 39 through line into line 20 leading into chamber 42, and all ofthe 3-methylcyclopentenes formed in reactor 18 are passed from line 84 through line 85 into line 10 to be converted vto methylcyclopentenes consisting essentially of 1methylcyclopentene in reactor 18. In this wise substantially the entire methylcyclopentene content of the hydrocarbon charge to the system is converted to 1methyl cyclopentene and eliminated from the system as the final product through valved line 61.

In the preferred modication of the invention isomerizing ,conditions within reactors 24 and 18 are preferably controlled to effect the production of methylcyclopentenes consisting essentially of 1 methylcyclopentene. Preferential formation of the l-methylcyclopentene isomer within reactors 24 and 18 is obtained by the maintenance of relatively mild olefin isomerization conditions therein. Suitable mild isomerization conditions are obtained by the use of the lower temperatures in the prescribed broad temperature ranges and the use of the less active isomerization catalysts. Thus suitable mild isomerization conditions comprise the use of a catalyst selected from the group comprising, for example, phosphoric acid type catalysts, bauxite, sulfuric acid treated adsorptive materials, at a temperature in the range of from about C. to about 350 C. Formation of cyclohexene in reactor 18 is optionally further suppressed by recycling a portion of the bottoms from fractionator 83 through valved lines 81 and 9| into line 19.

Although the detailed illustrative description of the invention has stressed the separation oi' the tertiary olefin, l-methylcyclopentene, by alkylating it with an alkylatable material, the

invention is in no wise restricted to the use of this specific method of effecting the lfmethylcyclopentene separation within chamber 42', and any of the conventional methods for effecting tertiary Iolefin separation from complex hydrocarbon mixtures may be resorted to in chamber 42 within the scope of the invention. Thus the hydrocarbon stream entering chamber 42 may be contacted with any suitable selectively reacting chemical agent such as sulfuric acid, halogen. hydrogen halide, etc. under conditions resulting in their selective reaction with l-methylcyclopentene and the formation of an adduct from which the tertiary olen, 1-methylcyclopentene, is separable in chamber 43. The adduct may be a sulfuric acid ester, a polymer, an alcohol, a

halide, an alkylate, or other adduct.

For the purpose of simplicity, all parts of apparatus not essential to a complete description of the invention, comprising, for example, pumps,

condensers, complex fractionating systems, ac-

cumulators, etc., have been omitted from thel drawing. It is to be understood that the apparatus shown may be modified as apparent to one skilled in the art Without departing from the spirit and scope of the invention.

The claimed invention is:

1. The process for the production of tertiary cyclic oleiins in a relatively high state of purity consisting essentially of l-methylcyclopentene from a, complex hydrocarbon mixture comprising l-methylcyclopentene and 4methylcyclopentene in admixture with close boiling hydrocarbons inseparable therefrom'by fractionation on a practical scale, which comprises contacting said mixture with a selectively reacting chemical agent under conditions effecting the selective interaction of l-methylcyclopentene and said chemical agent in a tertiary olefin removing zone, separating a fraction comprising the reaction products of said chemical agent and l-methylcyclopentene and a hydrocarbon fraction comprising unconverted 4-methylcyclopentene from the efiluence of said tertiary oleiin removing zone, contacting said 4 methylcyclopentene containing hydrocarbon fraction emanating from said tertiary olefin removing zone with a solid olefin isomerization catalysts under olen isomerizing conditions effecting the conversion of 4-methylcyclopentene to land 3-methylcyclopentenes in an olen isomerizing zone, fractionating B-methylcyclopentene and hydrocarbons comprising 1- and 4-methylcyclopentenes from the eluence of said isomerizing zone, recycling said S-methylcyclopentene back into said isomerizing zone, passing said hydrocarbons comprising 1- and 4-methylcyclopentenes fractionated from the eflluence of said isomerizing zone to said tertiary olen removing zone, and separating tertiary cyclic olens in a high state of purity consisting essentially of l-methylcyclopentene from said fraction comprising reaction products of said chemical agent and l-methylcyclopentene separated from the eiiluence of said tertiary olefin removing zone.

2. The process for the production of tertiary cyclic olens in a relatively high state of purity consisting essentially of 1-methylcyclopentene from a complex hydrocarbon mixture comprising l-methylcyclopentene and Li-methylcyclopentene in admixture with close boiling hydrocarbons inseparable therefrom by fractionation on a practical scale, which comprises contacting said mixture with an alkylatable compound under conditions eiecting the selective alkylation of saidI alkylatable compound with l-methylcyclopentene in a tertiary oleiin removing zone, separating a fraction comprising the alkylation products and a hydrocarbon fraction comprising unconverted 4-metnylcyclopentene from the efiluence of said tertiary olen removing zone, contacting said 4 methylcyclopentene containing hydrocarbon fraction emanating from said tertiary olefin removing zone with a solid olefin isomerization catalysts under olen isomerizing conditions effecting the conversion of 4-methylcyclopentene to 1- and B-methylcyclopentenes in an isomerizing zone, fractionating 3-methylcyclopentene and hydrocarbons comprising 1- and 4-methylcyclopentenes from the eiiluence of said isomerizing zone, recycling said 3methylcyclopentene back into said isomerizing zone, passing said hydrocarbons comprising 1- and 4-methylcyclopentenes fractionated from the eiiluence of said isomerizing zone to said tertiary olen removing zone, and liberating tertiary cyclic oleflns in a high state of purity consisting essentially of l-methylcyclopentene separable therefrom by fractionation on a practical scale, which comprises contacting said fraction with phenol under conditions eiecting the selective alkylation of phenol with l-methylcyclopentene in a tertiary olefin removing zone, separating a fraction comprising the alkylation product and a hydrocarbon fraction comprising unconverted 4methylcyclopentene from the eilluence of said tertiary oleiin removing zone, contacting said 4-methylcyclopentene-containing hydrocarbon fraction emanating from said tertiary olefin removing zone 'with a solid adsorptive aluminous material under oleiin isomerizing conditions effecting the conversion of 4methylcyclo pentene to 1- and 3-methylcyclopentenes in an isomerizing zone, fractionating S-methylcyclopentene and hydrocarbons comprising 1- and 4-methylcyclopentenes from the eiiluence of said isomerizing zone, recycling ,said 3-methylcyclopentene back into said isomerizing zone, passing hydrocarbons comprising 1- and 4-methylcyclopentenes fractionated from the eilluence of saidI isomerizing zone to said tertiary olefin removing zone, and liberating tertiary cyclic oleiins in a high state of purity consisting essentially of l-methylcyclopentene from said fraction comprising alkylation products separated from the efiluence of said tertiary oleiln removing zone.

4. The process for the production of cyclic oleiins in a relatively high state of purity consisting essentially of methylcyclopentenes from a complex hydrocarbon mixture comprising l-methylcyclopentene and 4-methylcyclopentene in admixture with close boiling open chain hydrocarbons inseparable therefrom by fractionation on a practical scale, which comprises contacting said hydrocarbon mixture with a selectively reacting chemical agent under conditions effecting the selective interaction of 1methylcyclopentene and said chemical agent in a tertiary olefin removing zone, separating a fraction comprising the reaction products of said chemical agent and i-methylcyclopentene and a hydrocarbon fraction comprising unconverted 4-methylcyclopentene from the eilluence of said tertiary olen removing zone, contacting said 4methylcyclopentene-containing hydrocarbon fraction emanating from said tertiary olefin removing zone with a solid olefin isomerization catalyst under olefin isomerizing conditions effecting the conversion of i-methylcyclopentene to 1- and 3methylcyclopentenes in an isomerizing zone, fractionating 3-methylcyclopentene free of any substantial amount of open chain hydrocarbons and a hydrocarbon fraction comprising 1- and 4-methylcycl'opentenes from the eiiluence of said isomerizing zone, passing said hydrocarbon fraction comprising 1- and 4-methylcyclopentenes fractionated from the eilluence of said isomerizing zone to said tertiary oleiin removing zone, and separating tertiary cyclic oleiins in a high state of purity consisting essentially of 1methycyclo pentene from said fraction comprising reaction products of said chemical agent and l-m'ethylcyclopentene separated from the eiiiuence of said tertiary olefin removing zone.

5. 'I'he process for the production of cyclic olens in a relatively high state of purity consisting essentially of methylcyclopentenes from a cornplex hydrocarbon mixture comprising 1-methylcyclopentene and 4-methylcyclopentene in admixture with close boiling hydrocarbons inseparable therefrom by fractionation on a practical scale, which comprises contacting said hydrocarbon mixture with an alkylatable compound under conditions effecting the selective alkylation of said alkylatable compound with said 1-methylcyclopentene in a tertiary olen removing zone, separating a fraction comprising the alkylation products and a hydrocarbon fraction comprising unconverted 4-methylcyclopentene from the efiiuence of said tertiary olefin removing zone, contacting said 4-methy1cyclopentene-containing hydrocarbon fraction emanating from said tertiary olefin removing zone with a solid olefin isomerization catalyst under olen isomerizing conditions Aeffecting the conversion of 4-methylcyclopentene to 1- and 3-methylcyclopentenes in an isomerizing zone, fractionating S-methylcyclopentene free of any substantial amount of open chain hydrocarbons and a hydrocarbon fraction comprising land 4methylcyolopentcnes from the efiiuence of said isomerizing zone, passing said hydrocarbon fraction comprising land 4-methylcyclopentenes fractionated from the efliuence of said isomerizing zone to said tertiary olefin removing zone, and liberating tertiary cyclic olei'lns in a high state of purity consisting essentially of 1-methylcyclopentene from said fraction comprising alkylation products separated from the eiiiuence of said tertiary olefin removing zone.

6. The process for the production of cyclic olefins in a relatively high state of purity consisting essentially of methylcyclopentenes from a complex hydrocarbon fraction comprising l-methylcyclopentene and 4-methylcyclopentene in admixture with close boiling hydrocarbons inseparable therefrom by fractionation on a practical scale, which comprises contacting said hydrocarbon fraction with phenol under conditions effecting the selective alkylation of phenol with l-methylcyclopentene in a tertiary olefin removing zone, separating` a fraction comprising the alkylation products and a hydrocarbon fraction comprising unconverted 4-methylcyclopentene from the eiiiuence of said tertiary olefin removing zone, contacting said 4 methylcyclopentene containing hydrocarbon fraction emanating from said tertiary olefin removing zone with a solid adsorptive aluminous material under olefin isomerizing conditions effecting the conversion of 4-methylcyclopentene to land S-methylcyclopentenes in an isomerizing ing alkylation products separated from the eiliu-v ence of said tertiary olefin removing zone.

7. The process for the production of tertiary cyclic olefins in a relatively high state of purity consisting essentially of l-methylcyclopentenes land 4methylcyclopentenes free. of any substantial amount of open chain hydrocarbons from the eiiiuence of said i'lrst isomerizing zone, contacting said higher boiling fraction with a treating agent under conditions effecting the selective removal of l-methylcyclopentene from said higher boiling fraction in a tertiary olefin separating zone, separating a fraction comprising said treating agent and l-methylcyclopentene and a hydrocarbon fraction comprising unconverted 4-methylcyclopentene from the eiiiuence of said tertiary olefin separating zone, contacting said 4-methy1- cyclopentene containing hydrocarbon fraction emanating from said tertiary olefin separating zone with a solid olen isomerization catalyst under olefin isomerizing conditions effecting the conversion of 4-methylcyclopentene `to 1- and 3- methylcyclopentenes in a second isomerizing zone, fractionating 3-methylcyclopentene and hydrocarbons comprising 1- and 4-methylcyclopentenes from the eiiluence of said second isomerizing zone, recycling said S-methylcyclopentene fractionated from the eilluence of the second isomerizing zone back into said second isomerizing zone, passing hydrocarbons comprising 1- and 4-methy1cyclopentenes fractionated from the eiiiuence of said rst and second isomerizing zones to said tertiary olefin separating zone, and separating tertiary cyclic olefins in a high state of purity consisting essentially of l-methylcyclopentene from said fraction comprising said treating agent and l-methylcyclopentene separated from the eiiiuence 0f said tertiary oleiin'separating zone.

8. The process for the production of tertiary cyclic olefins in a relatively high state of purity consisting essentially of l-methyl-cyclopentene from complex hydrocarbon mixtures vcomprising l-methylcyclopentene, 3methylcyclopentene and 4-methylcyclopentene in admixture with close boiling hydrocarbons, whichcomprises sepamethylcyclopentene boiling fraction comprising 1- and 4-methylcyclopentenes in admixture with close boiling open chain hydrocarbons from said mixture, contacting said lower boiling fraction with a solid olen isomerization catalyst under olefin isomerizing conditions effecting the conversion of 3- methylcyclopentene to 1- and 4methylcyclo pentenes in a first isomerizing zone, fractionating 1- and 4methylcyclo`pentenes free of any substantial amount of open chain hydrocarbons from the eiiluence of said first isomerizing zone, contacting said higher boiling fraction with a selectively reacting chemical agent under conditions effecting the selective interaction of 1- methylcyclopentene and said chemical agent in a tertiary olefin separating zone, separating a fraction comprising the reaction products of said chemical agent and l-methylcyclopentene and a 'hydrocarbon fraction comprising unconverted 4- methylcyclopentene from the efiluence of said tertiary olefin separating zone, contacting said 4-methylcyclopentene-containing hydrocarbon fraction emanating from said tertiary olefin separating zone with a solid olefin isomerization catalysts under olen isomerizing conditions effecting the conversion of 4-methy1cyclopentene to 1- and 3-methylcyclopentenes in a second isomerizing zone, fractionating 3-methy1cyclopentene and hydrocarbons comprising 1- and 4- methylcyclopentenes from the eluence of said second isomerizing zone, recycling said 3-methylcyclopentene fractionated from the eilluence of said second isomerizing zone back into said second isomerizing zone, passing hydrocarbons comprising 1- and 4-methylcyclopentenes fractionated from the eiiiuence of said first and second isomerizing zones to said tertiary olefin separating zone, and separating tertiary cyclic olens in a high state of purity consisting essentially of 1-methylcyclopentene from said fraction comprising reaction products of said chemical agent and 1methylcyclopentene separated from the effluence of said tertiary olen separating zone.

9. The process for the production of cyclic tertiary oleflns in a relatively high state of purity consisting essentially of l-methylcyclopentene from complex hydrocarbon mixtures comprising l-methylcyclopentene, S-methylcyclopentene and 4-methylcyclopentene in admixture with close boiling hydrocarbons, which comprises separating a lower boiling fraction comprising 3-methylcyclopentene in admixture with close boiling open chain hydrocarbons and a higher boiling fraction comprising 1- and 4methylcyclopentenes in admixture with close boiling open chain hydrocarbons from said hydrocarbon mixture, contacting said lower boiling fraction with a solid olen isomerization catalyst under olefin isomerizing conditions effecting the conversion of 3methyl cyclopentene to 1- and 4-methylcyclopentene in a first isomerizing zone, fractionating 1- and 4- methylcyclopentenes free of any substantial amount of open chain hydrocarbons from the eiiluence of said flrst isomerizing zone, contacting said higher boiling fraction with an alkylatable compound under conditions effecting the selective alkylation of said alkylatable compound with 1methylcyclopentene in a tertiary olefin separating zone, separating a fraction comprising the alkylation products and a hydrocarbon fraction comprising unconverted 4-methylcyc1o- -pentene from the elluence of said tertiary olefin separating zone, contacting said 4-methylcyclopentene-containing hydrocarbon fraction emanating from said tertiary olefin separating zone with a solid olefin isomerization catalyst under olefin isomerizing yconditions effecting the conversion of 4-methylcyclopentene to 1- and 3- methylcyclopentenes in a second isomerizing zone, fractionating -methylcyclopentene and hydrocarbons comprising 1- and 4-methylcyclopentenes from the eilluence of said second isomerizing zone, recycling said S-methylcyclopentene fractionated from the efuence of said second isomerizing zone back into said second isomerizing zone, passing hydrocarbons comprising 1- and 4-methylcyclopentenes fractionated from the effluence of said first and second isomerizing zones to said tertiary olefin separating zone, and

liberating tertiary cyclic oleiins in a high state of purity consisting essentially of 1methylcyclopentene from said fraction comprising alkylation products separated from the effluence of said tertiary olefin separating zone.

10. The process for the production of tertiary cyclic oleflns in a relatively high state of purity consisting essentially of 1-methylcyclopentene from complex hydrocarbon mixtures comprising 1-methylcyclopentene, -methylcyclopentene and 4-methylcyclopentene in admixture with close boiling hydrocarbons, which comprises separating a lower boiling fraction comprising S-methylcyclopentene in admixture with close boiling open chain hydrocarbons and a higher boiling fraction comprising 1- and 4-methylcyclopentenes in admixture with close boiling open chain hydrocarbons from said hydrocarbon mixture, contacting said lower boiling fraction with a solid adsorptive aluminous material under olen isomerizing conditions effecting the conversion of 3-methylcyclopentene to 1- and 4-methy1cyclopentenes in a first isomerizing zone, fractionating 1- and 4-methylcyclopentenes free of any substantial amount of open chain hydrocarbons from the eluence of said first isomerizing zone, contacting said higher boiling fraction with phenol under conditions effecting the selective alkylation of said phenol with l-methylcyclopentene in a tertiary olefin removing zone, separating a fraction comprising the alkylation product and a hydrocarbon fraction comprising unconverted 4-methylcyclopentene from the efuence of said tertiary olefin removing zone, contacting said 4-methylcyclopentene-containing fraction emanating from said tertiary olefin removing zone with a solid adsorptive aluminous material under olen isomerizing conditions effecting the conversionof 4-methylcyclopentene to 1- and 3-methylcyclopentenes in a second isomerizing zone, fractionating B-methylcyclopentene and hydrocarbons comprising 1- and 4- methylcyclopentenes from the eiliuence of said second isomerizing zone, recycling said 3-methy1- cyclopentene fractionated from the eiiluence of said second isomerizing zone back into said second isomerizing zone, passing hydrocarbons comprising 1- and 4-methylcyclopentenes fractionated from the efliuence of said rst and second isomerizing zones to said tertiary olefin removing zone, and liberating tertiary cyclic olens in a high state of purity consisting essentially of 1- methylcyclopentene from said fraction comprising alkylation products separated from the eilluence of said tertiary olefin removing zone.

GEORGE M. GOOD. HERVEY H. VOGE.

REFERENCES CITED The following references are of record in the me of this patent:

UNITED STATES PATENTS Number Name l Date 1,917,823 Britton et al July 11, 1933 2,265,583 Stevens et al Dec. 9, 1941 2.370.810 Morrell et al Mar. 6. 1945 

